Polyurethane foam compositions are typically prepared by reacting an isocyanate and a premix which consists of isocyanate-reactive components such as a polyol. The premix optionally also contains other components such as water, flame retardants, blowing agents, foam-stabilizing surfactants, crosslinkers and catalysts to promote the reactions of isocyanate with polyol to make urethane, with water to make CO2 and urea, and with excess isocyanate to make isocyanurate (trimer). The blowing agent in the premix is usually a liquid or gas with a boiling point sufficiently low to be vaporized by the heat released during the polymerization reaction. Examples of blowing agents useful in the production of insulating polyurethane foam include but are not limited to hydrofluorocarbons, hydrochlorocarbons, hydrofluoroolefins, chlorofluoroolefins, hydrochloroolefins, hydrofluorochloroolefins, hydrochlorofluorocarbons, formates, and hydrocarbons. The proper selection and combination of the components in the premix and the isocyanate can be useful for the production of polyurethane foam that is spray applied, poured in place, and used in applications such as refrigerators, freezers, hot water heaters, insulation panels, garage doors, entry doors, and other various applications where insulation is desired.
In the production of a polyurethane molded article the polyisocyanate is reacted with the active hydrogen containing compounds (e.g. polyol, primary or secondary amine, water) such that the number of isocyanate equivalents is approximately equal to the total equivalents of active hydrogen in the mixture.
Increasing concerns regarding the emission of low levels of aldehydes from polyurethane foams has resulted in emission standards by automobile manufacturers. The “Certipur” program has been adopted by the US and European polyurethane manufacturers trade groups to advance the safety, health and environmental performance of polyurethane foams. The limit of formaldehyde emission is 0.1 mg/m when measured using the ASTM method D5116-97 small chamber method with chamber conditioning for 16 h.
Aldehyde exposure limits, including limits specifically for formaldehyde and acetaldehyde, have been assigned by NIOSH and OSHA. These exposure limits are of significant interest to the automobile and slabstock industries in the overall efforts of these industries to enhance the air quality of the auto-cabin and of bedding materials. End users of automobiles and bedding materials may be exposed to VOCs (volatile organic compounds), including aldehydes, that may be emitted from the foams.
Japan Automobile Manufacturers Association (JAMA) has identified several VOCs, including formaldehyde and acetaldehyde, as contributors to foam emissions. Automotive foams may be required to pass heated chamber tests that measure for these aldehydes. Slabstock foam is required to pass the CertiPUR/LGA/-EUROPUR/IKEA tests which measure formaldehyde emissions. Thus there is a need in this art for polyurethane foams and materials used to make such foams that will emit much lower levels of aldehydes.
One example of conventional foam making materials is disclosed in U.S. Pat. No. 6,540,936 B1 that claims the use of polyethylene polyamines adsorbed onto silica as a vehicle for absorbing aldehydes from resin fiber such as polyester, nylon, polyurethanes and other natural and synthetic materials. Since these are solid aldehyde scavengers they cannot be used for production of polyurethane foams because only liquid materials can be pumped and mixed routinely in industrial processes that manufacture polyurethane products. EP 1,428,847B1 describes a process for reducing formaldehyde from polyurethane foams using polymeric substances containing primary and secondary amine groups. In US 2006/0141236 A1 hydrazine containing compounds have been used to reduce formaldehyde and acetaldehyde emission from polyurethane foams. Hydrazines are toxic and explosive limiting their use. A mixture of phenolic and phosphate antioxidants were claimed as compounds which prevent the formation of aldehydes in polyurethane foams and precursors in EP 1,874,853 B2. While these phenolic anti-oxidants prevent formation of aldehyde by oxidation of polyurethane precursors, these anti-oxidants do not remove aldehydes already present in the “pre-mix” solution used for making polyurethane foams. In US 2009/0326089 A1 compounds containing amido and cyano groups in the same molecule were described as formaldehyde scavengers in polyurethane compositions. Large amounts of the claimed molecules are required for the reduction of aldehydes. The combination of a primary amine compound with a tertiary amine catalyst to reduce formaldehyde emission from polyurethane foams is described in US 2011/0009512 A1 but this approach failed to reduce other aldehydes such as acetaldehyde. The industry need is for the reduction of formaldehyde, acetaldehyde, and acrolein emissions. Goh et. al. In U.S. Pat. No. 7,879,928 B2 describes a process for preventing the formation of aldehydic contaminants in polyurethanes and precursor by incorporating a phenolic antioxidant, aminic antioxidant,benzofuran-2-ones and phosphites or phosphonites into the formulation for polyurethane production. Haas et. al. in US 2012/0184639 A1 claimed the reduction of formaldehyde in polyurethane foams using semicarbazide containing compounds. The industry need is for the reduction of formaldehyde, acetaldehyde, and acrolein emissions. WO 2013/156237 A2 describes the use of guanidine containing additives for scavenging formaldehyde from polyurethane systems. Aldehyde scavengers are also disclosed in US 2009/0227758 but has the limitation of needing an additive in both the polyol and isocyanate. WO2015/050876A1 pre-treats and reprocesses the amine catalyst to lower the aldehyde emissions.
The previously identified patents and patent applications are hereby incorporated by reference.